Hair rollers have in the past normally had a round cross-section, i.e., they have been for rolling hair. They are usually heated by being placed over heating posts in a hair setter unit.
Though it has sometimes been considered advantageous to use other than round shapes in hair curlers, this apparently has not been the practice in hair rollers. Thus, for example, other than round shapes have been used in Nicol Ser. No. 459,146, Russell U.S. Pat. No. 1,397,332, Morenilla U.S. Pat. No. 1,486,786, Porter U.S. Pat. No. 3,516,420, and Demetrio U.S. Pat. No. 3,955,064. None of these patents are directed to hair rollers and none to the particular geometric structure used in my invention.